Salts of omage-cyanoguanidodithiocarbonic acid



Patented Feb. 6, 1945 w-cmnoennmnomrmm k cannomonom- V a v lack T. Thurston and. Donald side, Conn., assignors to American Cyanamid Company, New-York, N. Y., a corporation of N wing. Application June 7, 1943, I 1. ScrialNo.489,'988r a a itchin (015269-5300) This invention relates to new organic compounds andto their preparation. v We have discovered that the alkali metal salts of, dicyandiamide canbe caused to'react with carbon disulfide to yield new compounds which we have named alkali metal 'w-cyancg'uanidodithiocarbonates." I

The compounds of the present invention have in at. least one'of its tautomer'ic' forms the following' eneral formula:

Ms NH H v in which M1 is an alkali metal radical. I fItis quite likely, however, that the compounds may exist in The reaction takes place readily overa wide range of temperatures. The highe'r temperatures,

- asabove' 65 (1., should be avoided, howeverJince the product has a tendency todecompose at Bleevated temperatures. Ordinarily; temperatures ranging from to 65 C. :may be employed.

Under these temperature conditions the. reaction PTO whole or inpart in one or morertautomericlform's,

and, accordingly, we do not wish to be bound by the particular structure set forth. In viewof the above, our new compounds may'be called not" only w-cyanoguanidodithiocarbonates, but also wcyanoguanidodithioformates and w-cyanoguanyl- V 'dithiocarbamates. "We prefer the nomenclature first given, however, since it represents the most probable structure of our'compounds. n

The reaction employed by us to prepare these new compounds may be illustratedbythe following equation, using potassiumdicyandiamide and carbon disulfide:

H '1: K5 1 w NH 1 mN-s -n-Cm-CsF: o=N-"- p:. -"-N-cN' K g we to a l n',N--0--.N-0N The reaction of carbon disu'lfide with other alkali metal salts of dicyandiamide takes place similar- In carrying out our new reaction we prefer to suspend an alkali metal salt of dicyandiamide in a water miscible, non-hydroxylated solvent, such as acetone or pyridine, and add carbon disulfide thereto in amounts suflicient to completethe reaction. Other solvents such as alpha-, beta-, and gamma-picoline, quinoline, 2,4-lutadine, methylethyl ketone, etc. may be used with less efiectiveness. Although water may be present in the "reaction mixture, the amount thereof should be kept at a minimum since alkali metal salts of dicyandiamide tend to dissociate in the presence of water and other hydroxylated solvents.

may require from mm 12 hours at -10 C. to (L2 130 1.0 hour at C. At 15-t0 20? C the. reaction is usually complete in 15 minutes to l hourpthe time dependin somewhat upon the agitation of the reaction mixture, the physical condition ofthe dicyandiamide salt and-the quantity of reactants. Longer heating at moderate tempera- Wes y be practiced toinsure completion of .there'action. l

Instead of reacting a .'previously pnparedal kali metal dicyandiamide with carbon :disulflde,

.wemay prepare an alkali metal dicyandiainidein solution from aqueous solutions of alkali metal hydroxides and dicyandiamide by the method disclosed in the. copending application'oi on Donald W. Kaiser, Serial No. 440,87 9, fl1ed;April 2a, 1942, now Patent No'. 2,357, 261 ':datedA1 5 29, 1944, and add the carbon, disulfide to the solution containing the dicyandiamide salt. This procedure is advantageous in'that it eliminates the necessity'of first isolating the alkali metal dicyandiam-ide. This modification of our invention :islillustrated in Example 2. l a 1 Our" invention willlnow .be illustrated in greater particularity by means of the following/examples; It should be understood, however, that these-.ex--; wamples are givenfcr the purposes of illustration and are not to be construed .as limitinspur invention to the particular details described therein; 7

a 19 grams ofcarbon disulfide was added to s stirred suspension of 24.4 g. of potassium dicyandiamide in 200 cc. of acetone; The mixture was then heated to refluxingtempera'ture. Within a short time the outersurface of th potassium dicyandiamide crystals became yellow and theso lution light in color; Refluxing was continued for 2.5 hours. The mixture was cooled, the pale yellow-solid consisting of equi-molecular quantities of dipotassium w-cyanoguanidodithiocarbonate and dicyandiamide was filtered, washed with acetone and dried in a desiccator. The product was purified by dissolving it in ice water and then treating the solution with acetic acid. Upon acidification a precipitate believed to be 2-thio-4,6-diamino-'-1,3,5-thiadiazine was thrown down. The

precipitate was washed with water to remove 41- thiadiazine.

I Tola wa rm stirred solution of 27.8 g.

1 cyandiamide and other impurities and dried in an oven at 100 C. The washed precipitate can then be reconverted to dipotassium w-cyanoguanido dithiocarbonate by adding it to a solution of KOH in methyl alcohol or vigorously stirring it with a I slurry of KOH pellets in acetone. Light canary yellow .microcrystals of dipotassium w-cyanoguanidodithiocarbonate are thus obtained. The

salt is highly soluble in water. Chemical analysis 1'3 of the product gave results which checked close-V that it allows .us to obtain a product of high purity. This method also has the advantage in 1y with the theoretical values for dipotassium wcyanoguanidodithiocarbonate. The purified sample decomposed at 168 C.- -174ff 0., depending on the rate of heating.

Example 2 To a warm solution of 127.5 g. (3.0 moles) of 97% sodium hydroxide in 400 cc. of water was added 126 g. (1.5 moles) of dicyandiamide and,

Two clear layers;

then 1200 cc. of acetone. resulted. .The stirred mixture was cooled to .C. 'and'76 g: (1.0 mole) of carbon disulfide was :added in azperiod ofv 10 minutes.

.The yellow mixture-wasstirred for 1 hour after addition of the carbon disulfidef and then the acetone layer was removed byuse of a separatory furmel. The product, sodium .w-cyanoguanidodithiocarbonate, is found in the aqueous layer and the solution containing the salt may be used directly in the synthesis of'other organic compounds. If desired it may be recoveredfrom the aqueous layer-by acidification, with acetic or-hydrochlorie acid,

terial believed to be 2-thio-.-4,6-diamino-1,3,5-

The precipitate isrecovered by filwhich results in the precipitation of a solid matration and washed well with water and dried in added to a cold solution of NaOH in ethanol. This product may be isolated by filtration and washed with acetone or alcohol. Crystallization from ethaholgave beautiful light canary yellow plates-which decomposed'at'9 8-99i C. The material is extremely water soluble. I .Ercample '3 a (0.42 mole) of.85% :potassiumhydroxide in.500 cc. of

'methanol was added 32g. .(0.20 mole). of finely 2-thio-4,,6-diamino-1.3,5-thiadiazine prepared as described'in either of the preceding 7 examples- A light yellow bulky precipitate immediatelyseparated from solution. The material powdered an oven at 100.v Sodium w-cyanoguanidodithiocarbonate is regenerated when this material is that the 2-thio-4,6-diamino-1,3,5-thiadiazine can be prepared from the most easily obtainable and economical alkali metal wcyanoguanidodithio- 'carbonate. 'Any other desired alkali metal wcyanoguanidodithiocarbonate can then be read- "ily prepared by merely treating the 2-thio-4,6-

diamino-l,3,5-thiadiazine with an appropriate alkalimetal hydroxide by the method described inthis example. I

' Example 4 To 400 cc. of denatured ethyl alcohol was added 3517.85 g. (0.42 mole) of pulverized 97% sodium hydroxide. Before complete solution occurred, 32 g. (0.20 mole) of powdered Z-thiO- LG-diamino-l,3,5-thiadiazine was added. A large quantity of granular disodium w-cyanoguanidodithiocarbonate immediately separated from the slightly warm mixture. The slurry was stirred and heated to reflux, giving almost complete solu- ,tion. The yellow solution was filtered from dirt 'and the clear filtrate allowedto slowly cool. Beautifullpale yellow, plate-likeneedles of di..

sodium 'w-cyanoguanidodithiocarbonate were oba'ined which decomposed when heated at 98 -99 guanidodithiocarbonates which comprises treat-- .ing an alkali-metal ,dicyandiamidewith carbon disulfide in the presence .oLa. water insoluble,

was broken up and'.then stirred for 10 minutes before it'was 'filtered,.-'washed 'witli'a little meth anol, then acetonez and-allowed to air dry. The light canary yellow plates decomposed at 168 C. and weighed 36 g;'representing a 76.5% yield of. dipotas sium 'wcyanoguanidodithiocarbonate.

Thepreparatio-n of ournew compounds by the method just described o-ffirst' preparing an alkali metal w-cyanoguanidodithiocarbonate, -converting it to 2thio-4,6-diamino-1,3,5-thiadiazine and then reconverting. it back is advantageous in non-.hydroxylated solvent; 1 I

5. A method of preparing anjalkali -metal ocyanoguanidodithiocarbonate which comprises treating an alkali metalldicyandiamide with car- 'bon disulfide'in the presence of acetone,

6. A method of preparing an, alkali-metal wcyanoguanidodithiocarbonate which com-prises treating an alkali metal dicyandiamide with carbon 'disulfi'de in'the presence ofpyridine.

'7. A method of preparing alkali-metal o-cyano guanidodithiocarbonates which comprises the steps of suspending an alkali metal salt of dicyandiamide in a'wateremiscible, non-.hydroxylated solvent and adding thereto carbon disulfide while maintaining the reaction mixture at a temperature not in excess of about" C. and separating therefrom an alkali-metal w -cyanogua'nidodithiocarbonate.

. JACK T- THURSTON. DONALD w. KAISER. 

